Candle light dating
The color temperature of a white light source is the temperature in kelvins of a theoretical black body emitter that most closely matches the spectral characteristics of the lamp.
There are also downlights with internal reflectors designed to accept common 'A' lamps (light bulbs) which are generally less costly than reflector lamps.
Daylighting (using windows, skylights, or light shelves) is sometimes used as the main source of light during daytime in buildings.
This can save energy in place of using artificial lighting, which represents a major component of energy consumption in buildings.
Downlights can be incandescent, fluorescent, HID (high intensity discharge) or LED.
Track lighting, invented by Lightolier, was popular at one period of time because it was much easier to install than recessed lighting, and individual fixtures are decorative and can be easily aimed at a wall.
As early as 400,000 BCE, fire was kindled in the caves of Peking Man.